Michael and his team/army defeated? the Draco on Earth, and forced them to live underground, or retreat to the moon.

That's in reference to the colours of the spheres. Our moon being yellow, and possibly part of the empire still.

Would go a ways to explaining why we never went back, if we ever even went there...

I am following a few threads that are all quite synchronistic, and its blowing my wittle mind!

Quoting: BadHairDay

I read something a while back concerning the Draco mentality and beliefs of those times, and as far as the dragon being cast upon us, there is a belief that the inside of Ganimede will open up and the 'dragon beasts' from within will come to earth in an apocalyptic horror.